Hadith: Do not take two at a time, for indeed the Messenger of Allah (may Allah's peace and blessings be upon him) forbade taking two at a time. Then he said: Unless one asks for his brother's permission

عن جَبَلَةَ بنِ سُحَيْمٍ، قال: أَصَابَنَا عَامُ سَنَةٍ مع ابنِ الزبيرِ؛ فَرُزِقْنَا تمرًا، وكان عبدُ اللهِ بنُ عمرَ رضي الله عنهما يَمُرُّ بنا ونحن نَأْكُلُ، فيقول: لا تُقَارِنُوا، فإنَّ النبيَّ صلى الله عليه وسلم نهى عن القِرَانِ، ثم يقولُ: إلا أَنْ يَسْتَأْذِنَ الرجلُ أَخَاهُ.
[صحيح] - [متفق عليه]

Jabalah ibn Suhaym reported: We were afflicted with a year of drought at the time of ‘Abdullāh ibn Az-Zubayr. We were provided with dates. ‘Abdullāh ibn ‘Umar (may Allah be pleased with him) used to pass by us while we were eating and he would say: "Do not take two at a time, for indeed the Messenger of Allah (may Allah's peace and blessings be upon him) forbade taking two at a time." Then he said: "Unless one asks for his brother's permission."
Sahih/Authentic. - [Al-Bukhari and Muslim]

Explanation

Jabalah ibn Suhaym reported: We were afflicted with a year of drought with Ibn Az-Zubayr (may Allah be pleased with him) so he gave us dates. Ibn ‘Umar (may Allah be pleased with him) would pass by us while we were eating and inform us that the Prophet (may Allah's peace and blessings be upon him) forbade eating two dates at a time and any other food that is usually eaten one by one, when one is eating with a group, except with the permission of one's companions. Therefore, when you are with a group, do not eat two of the food that is normally eaten one by one – such as dates – at the same time because this harms your companions. So do not eat more than them unless you ask for their permission saying: Would you allow me to eat two dates at a time? If they agree, then there will be no harm in that. Note: A narration in Sahīh Al-Bukhāri reads: "He provided us with dates," meaning Ibn Az-Zubayr gave us the dates. In the narration of Al-Bayhaqi: "We were provided with dates," probably intending to say that the provider is Allah, the Exalted.